Be aware that faults can greatly increase the gridding time. We recommend that as few points as possible exist in the fault BLN file, preferably under 100 points. The more points you have in the fault file, the longer it will take to grid the data. Note that there is not a way to specify direction of movement or amount of displacement along a fault in Surfer, as they aren't specifically geological faults.

Once you have a vector file that defines all the fault traces, you can grid the data with the fault file:

Click Home | Grid Data | Grid Data.

Select your XYZ data file and click Open.

In the Grid Data dialog, select the X, Y and Z data columns.

Choose a gridding method that supports faults (Inverse Distance to a Power, Minimum Curvature, Nearest Neighbor, or Data Metrics). I recommend starting with either Inverse Distance to a Power or Minimum Curvature.